High frequency amplifier



Aug. 16, 1932. G. E. M. PERROUX ET AL 1,872,334

HIGH FREQUENCY AMPLIFIER Filed July 10, 1924 'l l l GEORGES EDME mmvmoux a VICTOR comu' INVENTOR5 aYj yQ w ATTORNEY Patented Aug. 16, 1932 .P.2\ T,E 1-u* OFFICE enonens EDME mancnnrnnnoux AND vIoToncoRnLLI, OF PARIS, Bunion; SAID PERROUX ASSIGNUB. TO .COMPAGNIE GENERALE DE TELEGRAPHIE SANS FIL, 0F rants, rnnnonn oonroRA'rroN role FRANCE? Y HIGH FREQUENCY AMPLirInn ,hppIicati'on filed July 10, 1924, Serial No. vea'nsje a mite m 11; 1923;

Ourpresent invention'rel'ates to improvements in high frequency amplifiers compris- 'in'g several vacuum tubes n cascade and more tive tuned stages;

Tuned high frequence amplifiers are well known in which the oscillating circuit between two consecutivevacuum tubes comprises an'inductauceconnected between anode and filament and a capacity in parallel across said inductance and in which the potential variations acrossthe oscillating circuit are applied on the grid-filament space of the following tube through a condenser, the mean potential of the said grid being 4 oscillating circuit '8, 9. is inserted in the confiXed by means of a grid leak resistance of high value connected. between the grid and a suitable point, such as, for instance, the minus pole of the heating battery.

Another well-known arrangement in high frequency amplifiers is obtained by connecting two consecutive tubes by means of a transformer, the primary or secondary or both of which are tuned to the frequency to be received by means of variable condensers across the terminals.

According to our present invention the oscillating circuit by means of which the amplifier is made selective is connected directly in the grid filament circuit of one tube and capacitively related to the plate of the preceding tube, the high tension direct current of this preceding valve being fed through a suitable inductance of such a value as to be practically independent of the frequency to be amplified.

Our invention will be best understood with reference to the accompanying drawing in which:

Figure 1 is a first embodiment of the invention. of the same invention. I The principal advantage of the herein described invention is to give greater selectivity in high frequency amplifiers.

On the accompanying drawing are shown two preferred embodiments of our invention applied to the interstage coupling of a tuned high frequency amplifier. On Figure poses...

overin some cases, particularly for receiving short waves it may be advantageous to Figure 2 is a second embodiment l'of the drawing 1 and 11 are two cascade connected amplifying tubes. Plate 2 of tube 1 'is connected on the one side with the positive pole 3 of the usual plate'battery through an inductance. 4 and on the other side through condenser 5 with grid 6 of tube 11. Grid '6 is connected with a suitable point having a well defined potential with respect to filament 7. (such as for instance, one of the terminals of said filament) through a resonating or oscillating circuit comprising an inductance 8 and a capacity 9 cheer both of these parts being variable for tuning pur- I On'Figure Q2 of the "drawingis shown a secondembodiment of our invention. The

.nection between. plate 2 and grid 6. In the case shown on this figure there must be provided a grid leakresistance of the order of a few megohms as shown at 10..

,Although the. circuit connections shown and described are preferred forms of our invention it is to be understood that we do notintendto limit ourselves to the precise embodiments given. In particular, condenser 5 and circuit- 8, 9 may be interchanged in the circuit of Figure 2 without departing from the conceptof'our invention. .Moreadjust the oscillating circuit 8, 9 at values different from those at which resonance with ductance and of a value which will combine What we claim as new and desire to secure by Letters Patent of the United States, is 95 1. A high frequency amplifier comprising in combination a plurality of three electrode tubesconnected in cascade, a plate circuit'including a choke coil associated with one tube, a tuned oscillating circuit compristion circuit comprising a fixed inductance anda variable condenser connected to the ln put circuit of one of said tubes, a condenser connected between the said oscillation circuit and the anode of a preceding tube, a choke coil in the anode circuit of said preceding tube, said oscillation circuit being adjusted to resonate at a frequency difierent I from the desired signal frequency and such that the resultant impedance of said oscillationcircuit is inductive. I

3. A radio frequency amplifier. comprising in combination, a plurality of multi-electrode tubes connected in cascade, an oscillation circuit comprising a fixed mductance and a variable condenser connected to the input circuit of one of said tubes, a condenser connected between the 'said oscillation circuit and .the anode of a preceding tube, a

. choke coil in the anode circuit of said preceding tube, said oscillation circuit beingv adjusted'toresonate at a frequencydifferent from the desired signal. frequencyand such thatthe resultant impedance of said oscillation clrcuit 1s inductive, said choke coil and condenser belng connected 1n series with each ciated with an initial tube, a closed oscillating circuit and a condenser connected in series between the grid to filament circuit of the second tube and plate of the initial tube and said oscillating circuit including adjustable means to resonate the oscillating circuit to a frequency other than a desired signal frequency to balance the inter-electrode capacity of the second tube.

7. A highfrequency amplifier comprising in combination, a plurality of three electrode tubes connected in a cascade, an aperiodic plate circuit associated with an initial tube, atuned oscillating circuit connected to the grid circuit of the second tube, means to capacitatively couple said aperiodic plate circuit of the initial tube to the grid-filament circuit of the second tube, the oscillating circuit being tuned to a frequency other than a the desired signal frequency thereby to vary the impedance of the tuned oscillating circuit to a value equal to that of the inter-electrode capacity of the second tube.

VICTOR CORELLI.

GEORGES EDME MARCEL PERROUX.

other, and with the control electrode of said first mentioned tube.

4. A radio frequency amplifier comprising 7 circuitof one of said tubes, a condenser con- ,nected between the said oscillatlon circuit and the anode of a preceding tube, a choke coil in the anode circuit of said preceding tube, said oscillation circuit being adjusted to resonate at a frequency different from the desired signal frequency and such that the resultant impedance of said oscillation circuit is inductive, said condenser being connected in series between the anode of said preceding tube and the control electrode of'said first mentioned tube.

5. A high frequency amplifier comprising in combination, a plurality of three electrode tubes connected in cascade, means to lmpress the output of one of said tubes upon the input of a succeeding tube, said means including anoscillating circuit tuned to a frequency other thana desired signal frequency, a high resistance, and an impedance between the oscillating circuit and the said tube output.

6. A high frequency amplifier comprising L 

